(1) Field of the Invention
A Time Code Interface (TCI) is used to provide the necessary timing information to external signal processors in order to generate target pulse widths, target pulse arrival times and lead words. (Leadwords provide the time of day in hours, minutes and seconds at predetermined intervals). The timing information for generation of the leadword is obtained from a Time Code Generator (TCG). Typically, an internally generated synchronization signal is synchronized with an externally generated 100 Kilo-pulses per second signal at a predetermined interval of time in order to generate a transfer signal. The transfer signal then transfers the leadword information from the TCG to the signal processing device. Typically, the TCI is hardwired within the signal processing devices.
(2) Description of the Prior Art
In U.S. Pat. No. 4,078,234, issued Mar. 7, 1978 entitled, "Continuous Wave Correlation Radar System" to Fishbein et al., there is described a continuous wave (CW) radar system in which the CW signal is simultaneously sinusoidally frequency-modulated and pseudo-random phase-modulated. The system includes means for generating a first, p-bit, pseudo-random binary code and means for phase-modulating a continuous wave microwave energy source with the first pseudo-random code. The system also includes means for generating a sinusoidal signal of a first frequency and means for frequency-modulating the microwave source with the first frequency. The system also includes means for generating a second, psuedo-random code which corresponds to the first code but which is delayed in time with respect thereto by a predetermined amount, and means connected to the means for deriving the video-frequency signal and to the second code generating means, for correlating the delayed version of the first code with the second code.
In U.S. Pat. No. 4,203,115, issued May 13, 1980 entitled, "Zero-Doppler Shift Positioning Technique" to Hannigan, there is described a system for determining the time at which a specific Doppler frequency occurs. A sampling time code is passed through a voltage limit sensor to a pulse triggering circuit which also serves as a buffer for interfacing with a data storage device. The pulse triggering circuit provides a series of pulses which are stored in the data storage device. Simultaneously, the time code is also stored in the data storage device for correlation with the pulses to set boundaries on the time of zero doppler or any other doppler frequency desired. These trigger pulses correspond to the time code and also provide a finer resolution of both the doppler signal and a finer resolution of the time at which the doppler signal was received.
In U.S. Pat. No. 4,238,785, issued Dec. 9, 1980 entitled, "Zero-Doppler Shift Positioning Technique", to Hannigan, a divisional application of U.S. Pat. No. 4,203,115, there is described a system for locating forward observation posts with respect to a base station. An artillery projectile or missile in flight emits a single continuous carrier frequency symmetrically modulated by a relative time code. The frequency emitted from the projectile or missile is doppler shifted above or below its basic frequency due to the velocity of the projectile. This doppler signal always goes through its basic frequency or zero doppler at a point which is representative of and identifies an observer's position in the horizontal or subtrack direction of the projectile. The relative time at which this zero doppler occurs for each observer is obtained from a time code transmission. The observer's position is provided with a means for storing this time code information. This time code is also used to identify the position of the projectile at any time during its flight.
In U.S. Pat. No. 4,797,677, issued Jan. 10, 1989, entitled, "Method and Apparatus for Deriving Pseudo Range From Earth-Orbiting Satellites", to MacDoran et al., there is described an apparatus that permits a user to derive his pseudo range from earth-orbiting, signal-transmitting satellites without knowledge of the code sequence of modulation carried by the signal, if any. In one embodiment of the invention, an omnidirectional antenna intercepts the signal from all the satellites in view at one time. The antenna is coupled to a radio receiver to recover selected components of the satellite signals. The radio receiver produces a sub-audio output signal which is connected to a clock interface unit, where the sub-audio signal is sampled, converted to digital form, and time tagged to identify the precise time at which each sample is taken. The time tagged digital samples are coupled to a digital computer where various functions are performed.
In U.S. Pat. No. 4,803,489, issued Feb. 7, 1989, entitled, "Method For Detecting A Camouflaged Object And System", to Giori, there is described a method and system for detecting an object hidden behind and/or under various combinations of optical and/or radar camouflage. The invention includes a pulsed radar system whose operation is initiated by a synchronizer or timing logic which, in general, controls the time sequence of transmissions, receiver gates and gain settings, and signal processing and display. The timing logic preferably includes a master clock and divider chain to provide the appropriate timing for recording radar returns without signal interference. To obtain location of the camouflaged object or objects, an aircraft location with respect to ground benchmarks is determined as a function of time. The straightforward trigonometric operation of adding the aircraft vector to that of the camouflaged object can be carried out either (i) in real time in the aircraft, or (ii) can be done later from time synchronized data. This data can be provided by a ground reference navigation system, such as INS, Doppler radar, GPS or other ground reference navigation systems. Accurately time-tagged aircraft location can be obtained from military tracking radars or from Air Force radar bomb sight tracking radars.